Rozhen Observation Calendar

Which nights are best for a target over the coming weeks. The astronomy mark (darkness × altitude × Moon) is computed for every night; the weather and the overall mark exist only where Open-Meteo has a forecast (the next four days) or ERA5 history (past nights) — the rest is honestly blank.

Best nights for V1057 Cyg: 05-18 (100), 05-19 (100), 05-20 (100), 05-21 (100), 05-17 (99) — by astronomy; check the weather when the night is within four days.

2039-04-22astronomy score per night — click a bar for that night2039-05-21

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-04-22 Fri	71	—	unknown	02:00–04:50 (good, 2.83 h)	87.3° 08:15	6.9	0%	72.7°
2039-04-23 Sat	71	—	unknown	02:00–04:45 (good, 2.75 h)	87.3° 08:15	6.84	0%	77.5°
2039-04-24 Sun	73	—	unknown	01:55–04:45 (good, 2.83 h)	87.3° 08:10	6.78	2%	82.7°
2039-04-25 Mon	75	—	unknown	01:50–04:45 (good, 2.92 h)	87.3° 08:05	6.72	6%	88.1°
2039-04-26 Tue	75	—	unknown	01:45–04:40 (good, 2.92 h)	87.3° 08:00	6.66	11%	93.6°
2039-04-27 Wed	77	—	unknown	01:40–04:40 (good, 3.0 h)	87.3° 07:55	6.6	17%	98.9°
2039-04-28 Thu	76	—	unknown	01:40–04:35 (good, 2.92 h)	87.3° 07:55	6.55	25%	104.0°
2039-04-29 Fri	77	—	unknown	01:40–04:35 (good, 2.92 h)	87.3° 07:50	6.49	34%	108.6°
2039-04-30 Sat	79	—	unknown	01:35–04:35 (good, 3.0 h)	87.3° 07:45	6.43	43%	112.5°
2039-05-01 Sun	77	—	unknown	01:35–04:30 (good, 2.92 h)	87.3° 07:40	6.37	53%	115.5°
2039-05-02 Mon	77	—	unknown	01:30–04:30 (good, 3.0 h)	87.2° 07:40	6.31	64%	117.2°
2039-05-03 Tue	77	—	unknown	01:30–04:30 (good, 3.0 h)	87.3° 07:35	6.26	74%	117.5°
2039-05-04 Wed	69	—	unknown	01:30–04:25 (good, 2.92 h)	87.3° 07:30	6.2	83%	116.1°
2039-05-05 Thu	66	—	unknown	01:30–04:25 (good, 2.92 h)	87.3° 07:25	6.14	91%	113.0°
2039-05-06 Fri	61	—	unknown	01:30–04:20 (good, 2.83 h)	87.3° 07:20	6.08	96%	108.3°
2039-05-07 Sat	56	—	unknown	01:30–04:20 (good, 2.83 h)	87.3° 07:20	6.03	100%	102.5°
2039-05-08 Sun	52	—	unknown	01:30–04:20 (good, 2.83 h)	87.3° 07:15	5.97	100%	95.8°
2039-05-09 Mon	49	—	unknown	01:40–04:15 (good, 2.58 h)	87.3° 07:10	5.91	97%	88.8°
2039-05-10 Tue	49	—	unknown	01:25–04:15 (good, 2.83 h)	87.3° 07:05	5.86	91%	82.0°
2039-05-11 Wed	51	—	unknown	01:15–04:15 (good, 3.0 h)	87.3° 07:00	5.8	83%	75.7°
2039-05-12 Thu	61	—	unknown	00:45–04:10 (good, 3.42 h)	87.3° 07:00	5.75	74%	70.3°
2039-05-13 Fri	72	—	unknown	00:40–04:10 (good, 3.5 h)	87.3° 06:55	5.69	63%	66.3°
2039-05-14 Sat	81	—	unknown	00:35–04:10 (good, 3.58 h)	87.3° 06:50	5.64	52%	63.6°
2039-05-15 Sun	88	—	unknown	00:30–04:05 (good, 3.58 h)	87.3° 06:45	5.59	42%	62.5°
2039-05-16 Mon	94	—	unknown	00:30–04:05 (good, 3.58 h)	87.2° 06:40	5.53	32%	63.0°
2039-05-17 Tue	99	—	unknown	00:25–04:05 (good, 3.67 h)	87.3° 06:40	5.48	23%	64.8°
2039-05-18 Wed	100	—	unknown	00:20–04:05 (good, 3.75 h)	87.3° 06:35	5.43	15%	67.8°
2039-05-19 Thu	100	—	unknown	00:15–04:00 (good, 3.75 h)	87.3° 06:30	5.38	9%	71.7°
2039-05-20 Fri	100	—	unknown	00:10–04:00 (good, 3.83 h)	87.3° 06:25	5.33	4%	76.3°
2039-05-21 Sat	100	—	unknown	00:10–04:00 (good, 3.83 h)	87.3° 06:25	5.28	1%	81.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-04-22&days=30"
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&days=30&format=csv" -o m31-calendar.csv

One row per night: score_astronomy always, score_weather / score only where a forecast or history exists (null otherwise, with weather_source saying which), best window, dark hours, Moon illumination and separation, transit. 7–60 nights. Errors: 400 with invalid_date or target_unresolved. Results are cached for six hours; calculation version 2026-10-10.1.